[DanEC]

It sounds like you aren't getting enough movement of the throw out bearing to disengage the clutch completely. That's usually the case when the gears are clashing or you can't go between gears at all with the engine running.

Possibly you have some air in system but it's also possible the clutch linkage is not adjusted properly. Basically, the rod between the fork and the slave cylinder needs to be extended enough so that the piston in the slave cylinder is retracted all the way back to bottom it out with the fork in contact with the throw out bearing. Then back off the rod length just a bit so that the throw out bearing will not be bearing on the clutch fingers. This should give you full stroke to disengage the clutch if the system is free of air. You should have a spring from the fork to the slave cylinder to help keep the bearing from riding on the clutch fingers.